An ACD function that is provided in an electronic private branch exchange or in an apparatus included in an electronic private branch exchange in related art are widely used in a call center, a user experience, a telephone reception window, and so on in which telephone calls are received. For example, as disclosed in “ACD System” in Japanese Unexamined Patent Application Publication No. 2004-266611, which is referred to as Patent Literature 1, “Button Telephone Device and Its Overflow-call Informing Method” in Japanese Unexamined Patent Application Publication No. 2006-253905, which is referred to as Patent Literature 2, and so on, the ACD function provides a mechanism for distributing incoming calls according to receiving situations of reception staff members (e.g., operators) so that each reception staff member (e.g., each operator) undertakes an equal amount of a reception task.